This invention relates to containers, and more particularly to marking components of metal cans.
Two piece metal cans include a can body on which a can end is attached by a seam. Commercial two piece beverage cans are formed by a drawing and ironing process that forms the body sidewall integral with the base. Three piece metal cans include a cylindrical body, each end of which has a can end attached by a seam.
Two piece beverage cans are produced in vast quantities for beverages and foods use; three piece beverage cans are produced in vast quantities for food uses. Accordingly, the components of the cans must be produced at high speeds.
Conventional beverage cans and many easy open food cans have pull tabs. Pull tabs are formed from metal sheet in a tab press. Because of the quantities required, conventional tab presses form many tabs at once in multiple lanes.
Typically, pre-lacquered coil of aluminum is fed into a shell press to form the can end shells. A pre-lacquered coil of aluminum is fed into a tab press to form the pull tabs. The shells and pull tabs are combined in a conversion press to form the unseamed can end.
Decoration of can ends, especially pull tabs, is known. For example, U.S. Pat. No. 6,105,806 discloses laser etching or removal of portions of a coating on a pull tab. U.S. Pat. No. 6,498,318 acknowledges difficulties in marking metal cans and discloses ablating metal pull tab stock. There is a need for improved tab marking technologies.